The moon cactus, or hibotan cactus is a unique ornamental plant which does not exist in nature (Altman Plants, n.d.). This cactus is completely a human design through a processes called plant grafting (Ombrello, n.d.; Altman Plants, n.d.). See “Grafting Cacti” near the bottom of the page for explanation of what grafting is and how it is done.
The name “Moon Cactus” actually refers to two separate cactus species. The bottom species, or the rootstock (Ombrello, n.d.), is known as Hylocereus undatus (Royal Horticultural Society, n.d.), and provides essential nutrients for growth to the entire plant (Altman Plants, n.d.). The top portion of the cactus, or the sicon (Ombrello, n.d.), is known as Gymnocalycium mihanovichii (Royal Horticultural Society, n.d.).
Mutants of this species do not produce chlorophyll and cannot photosynthesize (Ombrello, n.d.). Without the fusion to Hylocereus undatus, it would not survive (Ombrello, n.d.). The lack of chlorophyll allows the vibrant underlying pigments to show through (Altman Plants, n.d.), a similar concept to leaves changing colour in the fall.
Breeding new cultivars of Gymnocalycium mihanovichii is very common, especially in Korea (Park et al., 2012). Creating new breeds help to overcome some complications that can arise during plant grafting, such as slow growth and pigmentation (Park et al., 2012). These cacti are distinguished based on characteristics such as pigmentation, number of ribs, shape, globular diameter and number of offsets (Park et al., 2012). “Hwangseon”, a cultivar depicted to the right, is a yellow mutant created through the artificial breeding of two orange parents (Park et al., 2012). The selective breeding Gymnocalycium mihanovichii has produced a wide variety of a number of vibrantly coloured ornamental cacti (Park et al., 2012).
This succulent species, also known as the Nightblooming cactus, provides the stem and root system to the Moon Cactus (National Tropical Botanical Gardens, 2015). This species is a climbing epiphyte, meaning it establishes on the branches of another plant (National Tropical Botanical Gardens, 2015). This plant is native to the deciduous forests of Mexico, the West Indies, Central America and the northern portion of South America (National Tropical Botanical Gardens, 2015).
The stems of these plants contain chlorophyll and are photosynthetic, whereas the leaves are nonphotosynthetic brown spines (National Tropical Botanical Gardens, 2015). Hylocereus undatus produces very large white and yellow flowers that can grow to 25-30 cm in length (National Tropical Botanical Gardens, 2015). These flowers are very fragrant and bloom during the night and fall off the following day. These flowers are pollinated by bats during the night, and bees during the day and are used to make soup in China (National Tropical Botanical Gardens, 2015).
The fruit of this species is commonly known as dragon fruit (National Tropical Botanical Gardens, 2015). These fruits have a red fleshy outer skin with a soft white pulp interior containing small black seeds (National Tropical Botanical Gardens, 2015). Dragon fruit are edible and commonly used to make wine.
Grafting plants is both an art form and a science. It is the process of joining two living plant tissues to form one composite plant (Ombrello, n.d.). Grafting can be done on a number of different plant species and even occurs naturally between the roots of trees and shrubs (Ombrello, n.d.). Grafting is often done artificially between cactus species in order to create clones, new cultivars, repair damaged cacti, and for reproductive purposes (Ombrello, n.d.).
When grafting plants, the upper portion of the composite plant is referred to as the sicon and the bottom and underground portion of the plant is called the rootstock (Ombrello, n.d.). In order for the grafting to be successful, both the sicon and rootstock should be closely related (from the same species, genus or family) (Ombrello, n.d.).
Steps for Grafting Cacti
Cleanly cut the top portion of a small, upright cactus (rootstock) growing in a pot with a sharp, disinfected knife. Cut a bottom spherical portion from the bottom of the chosen sicon plant (Ombrello, n.d.).
Cutting the cactus will reveal the inner vascular cambium. This is the area where cacti will be united. Meristematic cells will grow, connecting the vascular tissues and allow nutrients and water to travel from the roots all the way to the top portion of the composite grafted plant (Ombrello, n.d.).
Align the two cacti so that some portion of the vascular cambium is in contact, this may cause the cacti to be off center (Ombrello, n.d.).
Place a rubber band around the sicon and the bottom of the pot to ensure contact is firm (Ombrello, n.d.).
Remove the rubber band after one or two months of growth .
Altman Plants. Cactus Collection: Grafted Cactus. Retrieved from: http://www.cactuscollection.com/info/cacti/grafted.html
National Tropical Botanical Gardens (2015). Meet the Plants: Hylocereus undatus. Retrieved from: http://www.ntbg.org/plants/plant_details.php?plantid=%2011884
Ombrello, T. Plant of the Week: Grafted Cactus. Retrieved from: http://faculty.ucc.edu/biology-ombrello/pow/grafted_cacti.htm
P.Park, M. Jeong, B. Yea, M. Kim, Y. Lee, P. Park, and B. Yoo. A New Grafted Cactus with Bright Yellow Color “Hwangseon”. Kor. J. Hort. Sci. Technol. 2012. 30(3):342-344 2012 DOI http://dx.doi.org/10.7235/hort.2012.11050
Royal Horticultural Society. Hylocereus undatus. Retrieved from: https://www.rhs.org.uk/Plants/8965/i-Hylocereus-undatus-i-(F)/Details
Royal Horticultural Society. Gymnocalycium mihanovichii. Retrieved from: https://www.rhs.org.uk/Plants/248072/i-Gymnocalycium-mihanovichii-i/Details
Wikicommons (2014). Dragon Fruit. Retrieved from: http://commons.wikimedia.org/wiki/Category:Dragon_fruit